[Launch Alert] Pegasus Launch Observations
Brian Webb
[email protected]
Mon, 30 Jun 2003 20:43:27 -0700
ASTRONOMY/SPACE ALERT FOR SOUTHERN CALIFORNIA
Brian Webb
Ventura County, California
E-mail: [email protected]
Web Site: http://home.earthlink.net/~kd6nrp
Reaching more than 2,060 e-mail addresses worldwide
2003 June 30 (Monday) 20:38 PDT
----------------------------------------------------------------------
PEGASUS XL/ORBVIEW 3 LAUNCH OBSERVATIONS
Last Thursday's airborne launch of a Pegasus XL rocket from an L-1011
occurred at 11:53 PDT (18:53 UTC). The launch point was 70 miles
southwest of Monterey from an altitude of 39,000 feet. The Pegasus
successfully placed OrbImage Corporation's OrbView 3 Earth imaging
satellite in a near-polar orbit.
Although the launch took place during daylight and was difficult see,
several people saw it and submitted the following launch observations.
Many of the reports were reformatted by the editor to improve
readability.
Jim Albers
Observing near Loma Prieta
"...Observation from 37 5.955, -121 51.382, 2900 ft, near Loma Prieta.
Did not see any aircraft contrails. Did not see rocket as it was
ascending, acquired rocket smoke trail shortly after launch.
Smoke trail was aligned approximately 30 degrees from vertical and was
visible from about 5 deg elevation to 10 degrees elevation without
visual aid.
Using 10x50 binoculars approximately another 5 degrees of dim trail
could be seen. Atmospheric winds twisted the trail in various
directions over several minutes, with main 5 degrees of trail
remaining visible for 10-15 minutes."
Gary Baker
Observing from Palo Alto
"Just witnessed today's Pegasus launch from Palo Alto, CA. It rose
above the Santa Cruz mountains to the SSW in exactly the right spot,
just a couple of minutes into the launch window (the drop itself
happened behind the mountains and out of view).
>From roughly 100 NM away, I could easily see the contrail left by the
first stage, but no light from the motor itself (same with 8x21
binoculars).
During the pause between 1st/2nd stage firing, light from the rocket
itself could be briefly seen, probably just a glint from reflected
sunlight.
The 2nd stage contrail was visible for only a few seconds, as (by
conjecture) the exhaust expanded quickly and no longer left a compact
trail to reflect the sun.
That was my first Pegasus launch, pretty nice."
"...I was surprised at how easy it was to see through our less-than-
transparent skies today."
Matt Beals
Observing from Salinas
"...We live in Salinas (20 miles from Monterey), and have never tried
to observe an air launch before.
We were too far away to see the rocket or L-1011 aircraft, and in
slightly the wrong position to see the actual launch. Our observation
began about T+3 minutes when a friend happened by and pointed at the
contrail hiding behind a tree from our observation point.
What we saw was this: a contrail arcing downwards, then upwards,
fading into the blue sky. The higher parts of the contrail were very
difficult to see. Looking out of the side of my eye (similar to
observing dim stars), I could see a very faint contrail leading very
high into the atmosphere. The lower portion of the contrail had
developed the characteristic zig-zag pattern by the time we saw it.
I took no pictures, but next time I'll be prepared to."
Jason Hatton
Observing from San Francisco
"...Myself & some of my colleagues got a decent view of launch through
to the early part of the second stage burn from the grounds of the VA
medical center in San Francisco. I was quite surprised how easy it was
to see considering the small size of the Pegasus and distance
(~110 nautical miles) from the launch point.
Visibility was excellent today, with only some light haze up to a few
degrees above the horizon. We picked up the trail of the Pegasus about
5 degrees above the horizon, it appeared to be going up vertically.
The rocket flame was not visible, the white exhaust trail was easy to
follow with the naked eye. The lower part of the trail persisted for
some minutes, twisting with the high altitude winds.
We could easily follow it to first stage burn out, when the trail
stop. A few second later we spotted a faint trail much higher - it was
now apparent the second stage was burning & the rocket was pitching
over. The trail appeared initially almost stationary, somewhat conical
in shape.
My guess is that the geometry of the trajectory improved visibility as
it arced over, allowing us to look almost directly down the rocket
exhaust. This gradually then tapered into a very thin faint trail
appearing to head downwards. Shortly thereafter the trail became
invisible.
Unfortunately, none of us had binoculars so it was impossible to try
to track it any further. I would estimate probably the first 30s of
the second stage burn was visible."
Kevin Ritschel
Observing from east of Hollister
"Saw it!
My location: ~36.39'/121W, on a ranch in the Diablo Range east of
Hollister.
Visible to the unaided eye for the first 1-2 minutes, tracked it in
binocs [binoculars] for about 2 minutes, lost visual contact after the
1st stage sep."
Todd Walker
Observing near San Simeon Point
"Viewed the Pegasus Launch from a spot on the coast just North of San
Simeon Point roughly 100 miles WSW from the launch coordinates. The
weather was absolutely incredible with warm temperatures and very calm
seas.
Launch occurred around 10 degrees above the horizon and we could
barely see the contrail through a dull haze layer that extended up to
about 15 degrees.
It flew level for a few seconds and then turned upward 45 degrees at
which point we could see a small bright orange flame as it climbed out
of the haze.
This lasted for a few moments and then we lost sight of it for good.
The bright white contrail was still visible when we left at 1:30."
----------------------------------------------------------------------
Southern California Astronomical Events
for 2003 July
Time*
Date (PST/PDT) Event
-------- --------- ------------------------------
JUL 5 03:00 Mercury Superior Conjunction
Mercury is on the far side of the Sun relative to Earth and is lost in
the Sun's glare. Superior conjunction marks the elusive planet's move
from the morning to the evening sky.
RASC Observer's Handbook 2003, pg. 89
JUL 6 19:32 First Quarter Moon
http://aa.usno.navy.mil/data/docs/MoonPhase.html
JUL 8-9 23:06-00:20** Lunar Occultation
The Moon occults (passes in front of) the star Alpha Librae. Star
disappears at 23:06 and reappears at 00:20
http://www.planetkc.com/bobgraze/2003d.zip
JUL 13 12:21 Full Moon
http://aa.usno.navy.mil/data/docs/MoonPhase.html
JUL 16 23:32** Lunar Occultation
The Moon occults (passes in front of) the star Tau Aquarii. Star
reappears at 23:32. The disappearance is not visible.
http://www.planetkc.com/bobgraze/2003d.zip
JUL 17 00:00 Moon-Mars Appulse
The Moon passes 0.3� north of Mars.
RASC Observer's Handbook 2003, pg. 89
JUL 21 00:01 Last Quarter Moon
http://aa.usno.navy.mil/data/docs/MoonPhase.html
JUL 26-27 --- Dark Sky Weekend
Optimum time this month for observing faint objects. Amateur
astronomers will congregate at dark observing sites
JUL 28 23:53 New Moon
Moon not visible
http://aa.usno.navy.mil/data/docs/MoonPhase.html
*All times given in 24-hour military format. For more information,
refer to:
http://home.earthlink.net/~kd6nrp/military.htm
**Time was computed for downtown Los Angeles. It may vary by several
minutes depending on your location.
----------------------------------------------------------------------
The following is a news release form the Jet
Propulsion Laboratory. The piece is a retrospective
on Seasat, a scientific satellite launched from
Vandenberg AFB a quarter century ago. Seasat is
still in orbit and easily seen with the naked eye.
AT 25, REMEMBERING A TREND SETTING SEAFARING SATELLITE
It only skippered the seas of space for a mere three months, but just
as Gilligan's "three-hour tour" has continued on in syndication for
decades, a salty satellite launched to study the oceans 25 years ago
this week by NASA's Jet Propulsion Laboratory, Pasadena, Calif., is
living on through the many missions it has spawned.
Seasat's tale began in the 1970s when a group of engineers and
scientists at JPL began work on an experimental satellite to study
Earth and its seas, using technologies being developed to study other
planets. The satellite's trip started from the not-so-tropic port of
Vandenberg Air Force Base, Calif., on June 26, 1978, aboard an
Atlas-Agena rocket. The five "passengers" that set sail that day
aboard Seasat included three prototype radar instruments and two
radiometers.
Seasat's "weather" got rough 106 days later, when a malfunction
unexpectedly ended the mission. Yet during its brief life Seasat
collected more information about the oceans than had been acquired in
the previous 100 years of shipboard research. It established
satellite oceanography and proved the viability of imaging radar for
studying our planet. Most importantly, it spawned many subsequent
Earth remote sensing satellites and instruments at JPL and elsewhere
that track changes in Earth's oceans, land and ice. Its advances were
also subsequently applied to missions to other planets.
"Seasat served to vault Earth science to where it is today, advancing
the study of such diverse disciplines as land and sea surface
topography, ice sheet and land movement, and sea surface winds," said
Dr. Frank Carsey, JPL research scientist. "It greatly advanced our
understanding of the El Nino and La Nina climate phenomena. It's
astonishing to think such a short mission could have such a tremendous
impact."
"Seasat had a major impact on future mission planning at NASA and
elsewhere," said Tony Spear, Seasat sensor manager. "Its prototype
radars and altimeter were precursors for many of today's more powerful
Earth observation satellites."
Seasat's experimental instruments included a synthetic aperture radar,
which provided the first-ever highly detailed radar images of ocean
and land surfaces from space; a radar scatterometer, which measured
near-surface wind speed and direction; a radar altimeter, which
measured ocean surface and wave heights; and a scanning multichannel
microwave radiometer measuring surface temperatures, wind speeds and
sea ice cover.
In oceanography, Seasat gave us our first global view of ocean
circulation, waves and winds, providing new insights into the links
between the ocean and atmosphere that drive our climate. For the
first time, the state of an entire ocean could be seen all at once.
Seasat's altimeter mapped ocean topography, allowing scientists to
determine ocean circulation and heat storage. The data also revealed
new information about Earth's gravity field and the topography of the
ocean floor. Since Seasat, advanced ocean altimeters on JPL's
Topex/Poseidon and Jason missions have been making precise
measurements of sea surface height used to study climate phenomena
such as El Nino and La Nina. Ocean altimetry has since become part of
weather and climate models, ship routing, marine mammal studies,
fisheries management and offshore operations.
Seasat's synthetic aperture radar monitored the global surface wave
field and revealed a wide spectrum of oceanic and atmospheric
phenomena from current boundaries to eddies.
Seasat's scatterometer gave us our first real-time global map of the
speed and direction of ocean winds, which drive waves and currents and
are the major link between the ocean and atmosphere. The technology
was later used on JPL's NASA Scatterometer and is now flying on JPL's
Quikscat spacecraft and its SeaWinds instrument on Japan's Midori 2
spacecraft. The data help forecasters predict hurricanes, tropical
storms and El Ninos.
Seasat's oceanographic mission also studied sea ice and its role in
controlling Earth's climate. Its synthetic aperture radar provided
the first high-resolution images of sea ice, measuring its movement,
deformation, age and thickness. Today, synthetic aperture radar and
scatterometers are both used to monitor Earth's ice from space.
Beyond the oceans, Seasat's synthetic aperture radar provided
spectacular images of Earth's land surfaces and geology. Seasat data
was used to pioneer radar interferometry, which can pinpoint land
surface changes such as those created by earthquakes, and to measure
land surface topography. Three JPL Shuttle Imaging Radar experiments
flew on the Space Shuttle in the 1980s/1990s. In 2000, JPL's Shuttle
Radar Topography Mission used the technology to create the world's
most detailed topographic measurements of more than 80 percent of
Earth's land surface. Beyond Earth, the technology was used on JPL's
Magellan mission, which mapped 99 percent of the previously hidden
surface of Venus, and the Titan radar onboard the JPL-built and
managed Cassini orbiter to Saturn.
Among the international missions with heritages tracing to Seasat are
the current Japanese Earth Resources Satellite 1, the Canadian/U.S.
Radarsat and the European Space Agency's Remote Sensing Satellites.
For more information on Seasat, visit:
http://www.jpl.nasa.gov/flash/seasat/intro.cfm.
JPL is a division of the California Institute of Technology, Pasadena.
----------------------------------------------------------------------
VANDENBERG LAUNCH STORY
Noted author and space analyst Jim Oberg recently called my attention
to an interesting story about a Vandenberg launch and eyewitness
reaction. It's posted at:
http://members.aol.com/tprinty2/bigsur.html
----------------------------------------------------------------------
SYMBOLS, ACRONYMS, AND ABBREVIATIONS
~ Approximately
deg Degrees
ft Feet
NM Nautical miles. A nautical mile is 6,076.115 feet in length.
The statute mile used in everday life is 5,280 feet long.
PDT Pacific Daylight Time
PST Pacific Standard Time
RASC Royal Astronomical Society of Canada
s Seconds
sep Separation
SSW South-southwest
T+ Elapsed time since launch
UTC Coordinated Universal Time (also called "Zulu")
VA Veterans Administration
WSW West-southwest